Study of bismuth sulphide films in Ni2+ containing solution using electrochemical quartz crystal microbalance

Abstract

The electrochemical reduction of Bi2S3 films deposited using the successive ionic layer adsorption and reaction method in a Bi(III) solution with a sulphidation agent Na2S was investigated in Ni2+ free background and Ni2+ containing electrolytes at different pH. This investigation was carried out by means of cyclic voltammetry, electrochemical quartz crystal microbalance and X-ray photoelectron spectroscopy. It has been established that during the reduction of a bismuth sulphide film in the Ni2+ free background solution the electrode mass decreases due to Bi2S3 film reduction to metallic Bi and the transfer of sulphide ions into the bulk of the solution. At pH=3, the Bi2S3 film reduces under the potential region from –0·2 to –0·4 V, while at pH=4 and 5 from –0·4 to –0·6 V. The processes occurring during the reduction of Bi2S3 film in the Ni2+ containing electrolyte depend on the electroreduction medium. At pH=3, the reduction of Bi2S3 film to metallic Bi and Ni2+ ions occurs simultaneously under the potential region of the cathodic current peak (–0·2 to –0·4 V). When pH is 4 or 5, the increase in electrode mass is caused by the incorporation of Ni2+ ions into the bismuth sulphide film with their partial reduction to the metallic or close to metallic state with the occurrence of structural changes in the film.